The invention relates to the combination of an accelerometer and an evaluation circuit connected thereto for controlling a safety device in an automobile.
Accelerometers, or electrodynamic acceleration sensors, are known; see, for example, U.S. Pat. No. 4,108,006 to Walter. Presently, accelerometers are used for the actuation of safety devices, for example, air bags in automobiles. Actuation of the safety device should be controlled so that actuation takes place not only upon the occurrence of an acceleration of given magnitude, either positive or negative as desired, but also when such acceleration takes place in a given direction, that is, within a prescribed directional sector. For example, actuation of an air bag is undesirable when a lateral impact occurs in an automobile. In addition, actuation should not occur when the automobile is hit from the rear.
An advantage of an accelerometer of the type disclosed in the Walter patent is the fact that the direction of the acceleration, as well as its magnitude, can be determined using a singular accelerometer. Accordingly, where it is desired to control a safety device upon impact not only of a given magnitude, but only from certain directions, the installation of a plurality of accelerometers and a combined electrical circuit to generate output signals is not required.